Mastering the mapping: The mapping is a powerful but difficult-to-tame tool. It generically maps the same kind of matter fields into each other, though described by different Lagrangians and coupled to different RBGs. After the identification of such a combination of gravity + matter is worked out (which does not depend on any particular symmetry of the problem under consideration), its application to finding new exact solutions from a known seed solution (the latter typically within GR) is outrageously simple. See [1]} for a conceptual discussion of this procedure.
